1. Technical Field
The present technology relates to a four-point seat belt device installed in vehicles such as automobiles.
2. Related Art
Seat belts for ensuring the safety of passengers are installed in vehicles such as automobiles. There are several types of seat belts including three-point seat belts, and also four-point seat belts which include shoulder belts to restrain both the right and left shoulders of the passenger.
Japanese Unexamined Patent Application Publication (JP-A) No. 2004-330975 discloses a technology which, in order to improve the restraint performance of four-point seat belts, sets the retraction force of the lap belts to be larger than the retraction force of the shoulder belts when retracting the lap belts that restrain the hips and the shoulder belts that restrain the shoulders.
JP-A No. 2010-58679 discloses a technology which, in order to correct the buckle position of the shoulder belts and the buckle position of the lap belts, detects the extended length of the lap belts and the extended length of the shoulder belts and then performs an adjustment control to reduce any differences in the extended lengths of the left and right lap belts and differences in the extended lengths of the left and right shoulder belts, based on the detected extended length.
However, the use of the previously described four-point seat belts may not guarantee the suitable restraint of passengers.
For example, there are cases in which the belt may reside on the upper area of the abdomen for passengers whose abdomen protrudes outwards. With the seat belt fastened in this way, there is a potential that the chest area above the abdomen will be significantly restrained while the area below the chest area will not be restrained when the seat belt is activated in the event of an accident or similar. Different from that of three-point seat belts, four-point seat belts are fastened in front of the passenger, and so the belts are loose and not positioned to the hips of the passenger when fastening the belts. For this reason, the passenger has to use their hands to hold and situate the hip belt toward their hips.
If the passenger is not of a body type in which the abdomen protrudes such that the belt resides on the upper area of the abdomen, it is still preferable to automatically restrain the passenger by pressing the hip belts to the hip without causing interference to the passenger.
In this way, the four-point seat belt device may adapt to passengers of various body types, and may restrain the body of the passenger without causing interference to the passenger.